This Presentation has the details about Identifiers in JAVA

1. Identifiers www.ustudy.in

4. Identifiers www.ustudy.in

6. 'a'. .'z', 'A'..'Z', '0'..'9', '_', $

7. Identifiers start with letter a1 is legal, 1a is not

8. can also start with underscore or dollar sign: _ $

9. Java is case sensitive. A and a are different.www.ustudy.in

11. Java reserved identifiers not a complete listboolean default for new break do if private case double import public catch else instanceOf return char extends int void class float long while www.ustudy.in

13. Must not be a Java keyword

14. See Appendix B for list of keywords

15. May begin with a letter or the underline character _

16. Followed by any number of characters, digits, or _ (note, no blanks)

17. Identifiers should be well chosen

18. use complete words (even phrases)

19. this helps program documentationwww.ustudy.in

22. Cannot be redefined or used in any other way in a program

23. Ex: public, private, if, class, throws

24. See p. 32 in LL for complete listwww.ustudy.in

26. Java API defines quite a few for us

27. e.g. System, Scanner, String, out

28. are used to represent names of variables, methods and classes

29. Cannot be keywords

30. We could redefine those defined in Java API if we wanted to, but this is generally not a good idea

31. Java IDs must begin with a letter, followed by any number of letters, digits, _ (underscore) or $ characters

32. Similar to identifier rules in most programming languageswww.ustudy.in

33. Example for Java Identifiers package javaidentifiers; /**** @author paul*/public class Main { /** * @param args the command line arguments */ public static void main(String[] args) www.ustudy.in

34. Program { // TODO code application logic here System.out.println(“Must start with a letter, ($), or connecting character (_)”); System.out.println(“Can not start with a number”); System.out.println(“No limits to the amount of characters for a identifier”); www.ustudy.in

35. Program System.out.println(“You can not use a Java Keyword”); System.out.println(“Case sensitive – IDENTIFER is different from identifier”); System.out.println(“Legal – see code”); int _$a; int x; int $j; int _____iiii; www.ustudy.in

36. Program System.out.println(“Illegal”); System.out.println(“int :6 – breaks rule 1″); System.out.println(“int ;J – breaks rule 1″); System.out.println(“int 6pp – breaks rule 2″); System.out.println(“int else – breaks rule 4″); } } www.ustudy.in

37. The End ….. Thank You ….. www.ustudy.in